Catalytic oxidation of fluorene



metres stares Parana. errata.

JOHN M. WEISS, OF NEW YORK, N. Y., AND CHARLES R. DOWNS, CLIZFFSIDE,

JERSEY, ASSIGINORS TO THE BARRETT COMBANY, A CORPORATION 0F NEW JERSEY.

CATALYTIC OXIDATION OF FLUORENE.

He Drawing.

'(2) New Jersey, have invented certain new and useful Improvements inCatalytic Oxidation of Fluorene, of which the following is aspecification.

This invention relates to the catalytic oxidation of fiuorene ordiphenylenemethane and to the production of a product of partialoxidation therefrom. It comprises the partial or selective oxidation of-fiuorene by oxygen either alone or mixed with diluents or by means ofan oxygen-containin gas.

in the presence of a catalyzer to form uorenone or diphenyleneketone.

The invention is based upon the discovery that by subjecting fifuorene,(3 11 to oxidation in the presence of an appropriate catalyzer, and atan appropriate temperature, a selective or partial oxidation thereoftakes place with the formation of an oxidation product known as aketonc. We have found that under proper conditions the fluorene may bechanged to fluorenone without eflecting the complete combustion of avery large proportion of the material treated, The invention may bepractlsed by sub ect1 ng the fluorene in the vapor phase mixed with airor with oxygen either alone or admixed with other diluent gases, or withcertain oxygen containing gases, to a suitable temperature in thepresence of certain catalyzers. It has been found that many oxids ofmetals are suitable for this purpose. More especially vanadiumcompounds, and more particularly the oxids of vanadium have been foundtobe especially useful as catalyzers in this process.

.. By suitably regulating diluents and operating with proper catalystsso that these conditions bear fixed relations to each other within widelimits, the degree of oxidation can be controlled where- Specificationof Letters Patent.

Application filed November 21,.1919. Serial No. ceases. 1

the conditions such as temperature, pressure and presence of Patented s.re, 1921..

by the fiuorene is oxidized in a particular manner to an extent short ofwhat is com monly, known as complete combustion, to produce fluorenone.

The invention will be explained in connection with the followingexample, which.

is given for illustrative purposes. It is not intended to limit theprocedure to the exact.

details given asthe process can be varied throughout wide limits withoutdeparting I from the spirit and scope of the invention.

A mixture of fiuorene and air in the vapor" phase is passed throughtubes at a tempera-, I- ture of about 300 Uto 700 (5., the tubes 1;containihg vanadium oxid deposited on crushed pumice with the resultthat fluorenone is produced. Instead of introducing oxygen as oxy en oftheair, oxygen gas may be used elther alone or diluted wlth nitrogen orother inert gas; the proportion of oxygen to fluorene may be varied; the

catalyzer may be deposited on crushed pumlce or other suitable powdered,granulated orfibrous material, which is chemically inactive and actsmerely as a mechanical distributer; the rate at which the mix-. ture ispassed through the tubes may be regulated to suitthe needs; the tubesIna be varied in length or diameter, or con ned spaces other than tubesmaybe used in which to place the catalyzer; instead of vanadium oxid,other compounds may be used as a catalyzer. It is essential that hotfluorene in the vapor phase shall come in contact with the catalyzer inthe presence of oxygen for the proper reaction to take place. Theintroduction of a diluent gas is a convenient way to assist inregulation of the reaction. It has been found that the pressure may bevaried throughout quite wide ranges, say very slightly below atmosphericup to considerably above atmospheric pressure with satisfactory results.

Theoretical considerations point to one molecule of fiuoren'e to twoatoms of ox gen as the proper proportions to produce uorenone fromfiuorene. The following equation is suggested as representing thereaction which takes place, though it is not desired to limit thereaction to any particular theory. The equatlon is given to ex- Where aconsiderable excess of fluorene isused over and above that which isoxldized, the remaining fluorene Wlll 1n part pass through practicallyunchanged, and the reaction gases will be correspondingly diluted by theexcess fluorene present during the reaction. The nitrogen ofthe air willhave a corresponding-diluent effect. Any steam if present, willsimilarly have a diluent effect, for example, in case moist air, insteadof dry air, is used in the process of the above specific example. Sincewater is practically always formed as a product some steam is present asa consequence.

The fluorene used should preferably be of high purity, or, if admixedwith impurities, it should be substantially free from impurities of sucha character as would prejudice the desired selective and partialcatalytic oxidation.

It will be evident that various types of apparatus may be used forcarrying out the process of the present invention and for bringing aboutthe necessary contact of the reacting gases with the catalyst and formaintaining the proper temperature for the catalytic reaction.Accordingly, we do not deem it necessary to describe in further detailsuch types of apparatus.

It will be evident also that the various conditions of the reaction arecapable of variation. Among these conditions may be mentioned thetemperature and pressure at which the reaction is carried out, the timeof contact of the reactive gases with the catalyst, the proportion ofcatalyst to the reacting gases, and the relative proportions of fluoreneand oxygen and of diluent. gases,

such as nitrogen. he reaction may thus be carried out at atmosphericpressure, or at increased or dim nished pressures. The

oxidizing effect can be modified by further diluting the reacting gases,as by returning the air, impoverished in oxygen by. the reaction, todilute the reacting gases in the further carrying out of the process, orby CH+ O CH plain the reaction as indicated by the results obtained.

o o c on cn c mixing oxygen with the air to increase the oxygen contentthereof, or by using oxygen contact of the reacting gases with thecatalyst can be varied by increasing the catalytic mass or by decreasingthe speed at which-the reactlng gases pass through or in contact withthe catalyst. These and like variations will correspondingly modify andaffect the catalytic oxidation.

Fluorenone. is apparently an intermediate product of the incompleteoxidation of fluorene. In the operation of this process under properconditions, there has been found to be very little complete-combustion,thus indicating that practically all of the fluorene which is oxidizedis changed to fluorenone. Any of the fluorene which passes through theprocess unchanged may be separated from the other products bysublimation, crystallization, distillation, etc., and may be againpassed through the reaction zone mixed with oxygen or mixed with a freshsupply of fluorene and oxygen, if desired, when more of it will beoxidized.

We claim:

1. The method of producing fluorenone which comprises oxidizing fluorenein the vapor phase at a temperature from about 300 to 700 C. with anoxygen containing gas in the presence of a metallic oxid as acatalyst.

'2. The method of producing fluorenone which comprises oxidizingfluorene in the vapor phase at a temperature of about 300 C. to 700 C.with an oxygen containing gas in the presence of vanadium oxid as acatalyst.

In testimony whereof we aflix our signatures.

